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Macromatic Industrial Controls

Located in Menomonee Falls, Wisconsin, Macromatic Industrial Controls engineers and manufactures industrial relays that control electrical processes and protects equipment from damaging or hazardous fault conditions. Macromatic provides solutions for almost any application in any industry. Macromatic’s products are used in the oil and gas, HVACR, pump control, material handling, irrigation, wastewater, mining, hoist, motor control, generator, lift and elevator industries and many more. As an independently-owned manufacturer of state-of-the-art control and monitoring products for over 40 years, Macromatic takes pride in its short lead-time, flexible product design, and exceptional technical support.

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Product Overview

Alternating Relays are used in special applications where the optimization of load usage is required by equalizing the run time of multiple loads. Identical loads are used for the same job—a standby unit is available in case the
first load fails. However, an idle load might deteriorate due to lack of use and provide no safety margin. Alternating relays prevent this by assuring that multiple loads get equal run time. In addition, there are situations where a need arises to have multiple loads on at the same time for additional capacity if one load cannot keep up with demand.

This alternating action is normally initiated by a control switch such as a float switch or pressure switch. Each time the initiating switch is opened, turning off a load, the alternating relay will change state, thus alternating the multiple
loads.

Typical applications include pumps with float switches as the initiating contact or compressors with pressure switches or thermostats as the initiating contact.

Macromatic offers two types of Alternating Relays:

Duplex: For controlling two loads, both plug-in & inner-door mounting, in SPDT, DPDT and DPDT Cross-Wired output configurations

Triplex: For controlling three loads, plug-in mounting

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ARP Series
ARP Series X wired
ARF Series
ARP Series - S.O.S.O
ATP Series
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DPDT Cross Wired Duplexor.jpg
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Duplex SPDT & DPDT

In the off state, the Control Switch is open, the Alternating Relay
is in the LOAD 1 position, and both LOAD 1 & LOAD 2 are
off. The red LED marked “LOAD 1” is ON. When the Control
Switch closes, it energizes LOAD 1. As long as the Control
Switch remains closed, LOAD 1 remains energized. When
the Control Switch opens, LOAD 1 is turned off and the Alternating Relay toggles to the LOAD 2 position. The red LED
marked “LOAD 2” is ON. When the Control Switch closes
again, it energizes LOAD 2. When the Control Switch opens,
LOAD 2 is turned off, the Alternating Relay toggles back to
the LOAD 1 position, the red LED marked “LOAD 1” is ON,
and the process can be repeated.

A DPDT Alternating Relay is the same as a SPDT but with
an extra set of NO & NC contacts. As shown in to right,
these extra contacts can be used for pilot lights or other
indications.

Duplex DPDT Cross-Wired

In the off state, both the LEAD Switch and the LAG Switch
are open, the Alternating Relay is in the LOAD 1 position,
and both LOAD 1 & LOAD 2 are off. The red LED marked
“LOAD 1” is ON. When the LEAD Switch closes, it energizes
LOAD 1. As long as the LEAD Switch remains closed, LOAD
1 remains energized. If the LAG Switch closes, it energizes
LOAD 2. When the LAG Switch opens, LOAD 2 is turned off.
When the LEAD Switch opens, LOAD 1 is turned off and the
Alternating Relay toggles to the LOAD 2 position. The red
LED marked “LOAD 2” is ON. When the LEAD Switch closes,
it turns on LOAD 2. If the LAG Switch closes, it will energize
LOAD 1. When the LAG Switch opens, LOAD 1 is turned
off. When the LEAD Switch opens, LOAD 2 is turned off, the
Alternating Relay toggles back to the LOAD 1 position, the
red LED marked “LOAD 1” is ON, and the process can be
repeated. NOTE: the LEAD switch must always close before
the LAG switch and must always open after the LAG switch.

The diagram at right illustrates a type of operation known
as “Sequence On - Simultaneously Off (S.O.S.O.)”-the two
loads are energized sequentially, but remain on together until
the OFF switch is opened. In the initial OFF state, all three
switches are open, the Alternating Relay is in the LOAD 1
position, and both loads are off. No action happens with the
Alternating Relay or either load when the OFF Switch closes.
When the LEAD Switch closes, Load M1 turns on. When the
LAG Switch closes, Load M2 turns on. Both loads remain
on as long as all three switches are closed. When the LAG
Switch opens, Load M2 remains on because the OFF Switch
is still closed. When the LEAD Switch opens, Load M1
remains on because the OFF Switch is still closed. When the
OFF Switch opens, both Load M1 and Load M2 are turned off
simultaneously. The Alternating Relay toggles to the LOAD 2
position. The entire cycle is then repeated, but with Load M2
energized first followed by Load M1.

NOTE:
Both drawings shown are for DPDT Cross-Wired units with input voltage connected to Pins 3 & 6. For DPDT Cross-Wired units with input voltage connected to Pins 5 & 6, visit www.macromatic.com/ar-apps.

Triplexor

All three switches are open and all loads are off. When the
LEAD Switch closes, it energizes LOAD 1. As long as the
LEAD Switch remains closed, LOAD 1 remains energized. If
the LAG Switch closes, LOAD 2 is energized. If the LAG2
Switch closes, it energizes LOAD 3. Each load is turned off
in sequence as the switches are opened. The entire cycle
is then repeated, but with LOAD 2 energized first followed
by LOAD 3 and then LOAD 1. NOTE: Power for outputs is
supplied from L connection, not through input switches.


Drawing references terminal numbers on 8 pin products